title: Environmental feedbacks and engineered nanoparticles: mitigation of silver nanoparticle toxicity to Chlamydomonas reinhardtii by algal-produced organic compounds.
abstract: The vast majority of nanotoxicity studies measures the effect of exposure to a toxicant on an organism and ignores the potentially important effects of the organism on the toxicant. We investigated the effect of citrate-coated silver nanoparticles (AgNPs) on populations of the freshwater alga Chlamydomonas reinhardtii at different phases of batch culture growth and show that the AgNPs are most toxic to cultures in the early phases of growth. We offer strong evidence that reduced toxicity occurs because extracellular dissolved organic carbon (DOC) compounds produced by the algal cells themselves mitigate the toxicity of AgNPs. We analyzed this feedback with a dynamic model incorporating algal growth, nanoparticle dissolution, bioaccumulation of silver, DOC production and DOC-mediated inactivation of nanoparticles and ionic silver. Our findings demonstrate how the feedback between aquatic organisms and their environment may impact the toxicity and ecological effects of engineered nanoparticles.
authors.affiliation: Department of Ecology, Evolution and Marine Biology, University of California Santa Barbara, Santa Barbara, California, United States of America.
authors.forename: Louise M
authors.initials: LM
authors.lastname: Stevenson
authors.forename: Helen
authors.initials: H
authors.lastname: Dickson
authors.forename: Tin
authors.initials: T
authors.lastname: Klanjscek
authors.forename: Arturo A
authors.initials: AA
authors.lastname: Keller
authors.forename: Edward
authors.initials: E
authors.lastname: McCauley
authors.forename: Roger M
authors.initials: RM
authors.lastname: Nisbet
mesh_terms: D061249:Batch Cell Culture Techniques; D002244:Carbon / Q000494:pharmacology; D016825:Chlamydomonas reinhardtii / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D002951:Citrates / Q000494:pharmacology; D004784:Environmental Monitoring; D005246:Feedback; D007477:Ions; D053768:Metal Nanoparticles / Q000633:toxicity*; D008954:Models, Biological; D036103:Nanotechnology; D009930:Organic Chemicals / Q000378:metabolism* / Q000494:pharmacology*
chemical_list: D002951:Citrates; D007477:Ions; D009930:Organic Chemicals; D002244:Carbon